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Search Results: 1 - 10 of 5941 matches for " Reza Bozorgpour "
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Study and Analysis of Obstacles and Challenges Facing Ship-Repair Industry in Iran  [PDF]
Reza Bozorgpour, Behrouz Omaraee, Mohsen Vaez Zadeh Asadi
Open Journal of Marine Science (OJMS) , 2017, DOI: 10.4236/ojms.2017.74034
Nowadays, shipping industry which is the backbone of economic development has affiliated to ship maintenance and repair industry. This industry provides technical maintenance services to ships in a way to enable them to meet the requirements and regulations of the International Maritime Organization and maintaining the vessels at high technical standard & continual seaworthiness condition. Maintaining the minimum requirement of classification societies on the ships is solely taken place with repairs. The research method is an applied study in sake of aim and a descriptive study in sake of nature. This research has been conducted to examine causes and factors contributed to failures repairing in dry docks in the country; using the obtained results, an approach has been presented to reduce obstacles existing in country and reach to standard international levels. The problems include lack of suitable strategy, lack of government support, governmental facet of the structure of this sector, cumbersome laws, customs problems, lack of specialized workshops, low levels of technology and lack of new technology etc. Thus, by taking amendment to the cumbersome rules, taking advantage of industry and modern technology experts, increasing productivity and competitiveness, centralizing active domestic and foreign workshops at private sector, facilitating timely supply of parts and accessories, using research and development sector, increasing quality, reducing costs and repair time, selecting secure industrial- trade partner and etc. can pave the way in this context.
A Note on Change Point Detection Using Weighted Least Square  [PDF]
Reza Habibi
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.210182
Abstract: This paper is concerned with the application of weighted least square method in change point analysis. Testing shift in the mean normal observations with time varying variances as well as of a GARCH time series are considered. For both cases, the weighted estimators are given and their asymptotic behaviors are studied. It is also described that how the resampling methods like Monte Carlo and bootstrap may be applied to compute the finite sample behavior of estimators.
Exponential B-Spline Solution of Convection-Diffusion Equations  [PDF]
Reza Mohammadi
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.46129
Abstract: We present an exponential B-spline collocation method for solving convection-diffusion equation with Dirichlet’s type boundary conditions. The method is based on the Crank-Nicolson formulation for time integration and exponential B-spline functions for space integration. Using the Von Neumann method, the proposed method is shown to be unconditionally stable. Numerical experiments have been conducted to demonstrate the accuracy of the current algorithm with relatively minimal computational effort. The results showed that use of the present approach in the simulation is very applicable for the solution of convection-diffusion equation. The current results are also seen to be more accurate than some results given in the literature. The proposed algorithm is seen to be very good alternatives to existing approaches for such physical applications.
Complex Matter Space and Relativistic Quantum Mechanics  [PDF]
Reza Ahangar
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.521317
Abstract: The Special Relativity Theory cannot recognize speed faster than light. New assumption will be imposed that matter has two intrinsic components, 1) mass, and 2) charge, that is M = m + iq. The mass will be measured by real number system and charged by an imaginary unit. This article presents a Complex Matter Space in Relativistic Quantum Mechanics. We are hoping that this approach will help us to present a general view of energy and momentum in Complex Matter Space. The conclusion of this article on Complex Matter Space (CMS) theory will lead help to a better understanding toward the conversion of mass and energy equation, unifying the forces, and unifying relativity and quantum mechanics.
Spatial Reactor Dynamics and Thermo Hydraulic Behavior Simulation of a Large AGR Nuclear Power Reactor in Response to a Reactivity Step Change Disturbance  [PDF]
Mohammad Reza Ansari, Reza Marzooghi
Energy and Power Engineering (EPE) , 2011, DOI: 10.4236/epe.2011.33047
Abstract: In this article, two-dimensional partial differential equations with time representation of nuclear power reactor kinetics are considered for spatial reactor dynamics and thermo hydraulic behavior analysis of a large thermal advanced gas cooled reactor (AGR) type used for nuclear power generation. The equations include the neutron flux equation and delayed neutron precursor concentration, together with taking into account the equations to represent the thermo hydraulic behavior of the fuel, coolant and moderator temperatures. These equations are solved numerically using the finite difference method. For time propagation, an implicit method is applied. The desired initial condition for the reactor to stay at stable critical condition is established by finding the correct value of reactivity. The reactivity disturbance effect in the reactor is studied for different cases and presented for high reactivity values. The model was developed for the analysis of a large AGR with 2000 MWe for future power generation. The results show that the model not only behaves stably but also predicts the results physically for all the various parameters.
3D Analysis and Investigation of Traffic Noise Impact from Hemmat Highway Located in Tehran on Buildings and Surrounding Areas  [PDF]
Hamid Reza Ranjbar, Ali Reza Gharagozlou, Ali Reza Vafaei Nejad
Journal of Geographic Information System (JGIS) , 2012, DOI: 10.4236/jgis.2012.44037
Abstract: This study analyzes and investigates the impact of traffic noise on high rise buildings and surrounding areas by the side of Hemmat Highway that links west of Tehran to the east. In this study, a 3D traffic noise simulation model is applied on a GIS system. Visualized noise levels are formulated by the proposed model for noise mapping on all surfaces of the buildings and surrounding ground in a 3D platform. The investigation shows that there is a high traffic noise impact on the foreground and front facades of buildings, rendering these areas unsuitable for residential purposes. The ground area by the sides of buildings and the building side panels receive a lower noise impact. Most of these areas are still not acceptable for residential and even commercial use, only the back yards and back panels, have the lowest traffic noise impact. It also shows that the building height is not an effective factor for reducing motorway noise on the upper part of the building. Finally, construction cantilever barriers with a height of seven meters, close to the outer edge of the highway was presented as an effective way to reduce noise within the allowable range of noise pollution for commercial and residential purposes.
Statistical Modeling of Pin Gauge Dimensions of Root of Gas Turbine Blade in Creep Feed Grinding Process  [PDF]
Ahmad Reza Fazeli
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.28081
Abstract: Creep feed grinding is a recently invented process of material handling. It combines high quality of the piece surface, productivity, and the possibility of automatic control. The main objectives of this research is to study the influences of major process parameters and their interactions of creep feed grinding process such as wheel speed, workpiece speed, grinding depth, and dresser speed on the pin gauge dimensions of root of gas turbine blade by design of experiments (DOE). Experimental results are analyzed by analysis of variance (ANOVA) and empirical models of pin gauge dimensions of root are developed. The study found that higher wheel speed along with slower workpiece speed, lower grinding depth and higher dresser speed, cause to obtain best conditions for pin gauge dimensions of root.
Recurrent Polynomial Neural Networks for Enhancing Performance of GPS in Electric Systems  [PDF]
Mohammad Reza MOSAVI
Wireless Sensor Network (WSN) , 2009, DOI: 10.4236/wsn.2009.12015
Abstract: Global Positioning System (GPS) is a worldwide satellite system that provides navigation, positioning, and timing for both military and civilian applications. GPS based time reference provides inexpensive but highly-accurate timing and synchronization capability and meets requirements in power system fault location, monitoring, and control. In the present era of restructuring and modernization of electric power utilities, the applications of GIS/GPS technology in power industry are growing and covering several technical and man-agement activities. Because of GPS receiver’s error sources are time variant, it is necessary to remove the GPS measurement noise. This paper presents novel recurrent neural networks called the Recurrent Pi-Sigma Neural Network (RPSNN) and Recurrent Sigma-Pi Neural Network (RSPNN). The proposed NNs have been used as predictor in GPS receivers timing errors. The NNs were trained using the dynamic Back Propagation (BP) algorithm. The actual data collection was used to test the performance of the proposed NNs. The ex-perimental results obtained from a Coarse Acquisition (C/A)-code single-frequency GPS receiver strongly support the potential of the method using RPSNN to give high accurate timing. The GPS timing RMS error reduces from 200 to less than 40 nanoseconds.
Proposing a New Metric for Collaborative Filtering  [PDF]
Arash Bahrehmand, Reza Rafeh
Journal of Software Engineering and Applications (JSEA) , 2011, DOI: 10.4236/jsea.2011.47047
Abstract: The aim of a recommender system is filtering the enormous quantity of information to obtain useful information based on the user’s interest. Collaborative filtering is a technique which improves the efficiency of recommendation systems by considering the similarity between users. The similarity is based on the given rating to data by similar users. However, user’s interest may change over time. In this paper we propose an adaptive metric which considers the time in measuring the similarity of users. The experimental results show that our approach is more accurate than the traditional collaborative filtering algorithm.
The Impact of First Language Intonational Clue Selection on Second Language Comprehension  [PDF]
Leila Barati, Reza Biria
Open Journal of Modern Linguistics (OJML) , 2011, DOI: 10.4236/ojml.2011.12005
Abstract: Comprehension is closely related not only to the knowledge of words and syntax, but also the pragmatic concerns of the discourse. The purpose of the present study was to investigate the impact of the intonational clues selection of Iranian teenagers' and young adults’ Persian listening comprehension ability on their English learning as a second language. According to Buck (2003), in listening comprehension the input in the form of sounds and intonational clues often conveys additional information. In this study 60 male and female teenagers (13 - 19) and 60 male and female young adults (20 - 26) were selected randomly based on Oxford Placement Test (OPT). Each group was randomly assigned to two sub groups; namely, experimental (EX) and control groups (CG), 15 participants in each group. During the study two fiction and non-fiction passages, at first in Persian and then in English, were read to participants. The passages for participants in CG were read without applying speaker’s intonation changes but they were read for participants in EX with applying speaker’s intonation changes. In this study factors as age and gender are important because the results showed that the difference between two groups with different age ranges was significant, and participants’ inferencing, correct clue selection and listening comprehension ability in the experimental group was superior to the control group in the first language (Persian) and it also influenced positively second language learning and inferencing ability (English).
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